If you consider, consider also to buy the one with the lowest storage. It is not that hard to upgrade it yourself. You end up with even more storage than the most expensive model (if you're planning to buy that one). You only miss the anti-glare etched glass and a custom profile background. But you can buy a anti-glare screenprotector if needed.
I'm thinking I would get the 256gb version and 512gb SD card ti start with, so I don't have to upgrade right away. It's great that upgrading is even an option though.
Building off what the other guy said, you'll want to upgrade the hard drive when you can, I got the 64gb one and got two 500+ gb sd cards, but the shaders needed for the games can only be stored on the internal memory from what I've seen, and even having a few larger games installed has filled up the majority of my internal storage, to a point where I couldn't download updates for flatpacs or run some games due to so LITTLE storage. I'm going to look into upgrading my drive because it became such a problem for me